Appliance timers are commonly used in many household appliances, such as dishwashers, clothes washers, and clothes dryers. The appliance timer controls operation of the appliance by actuating and deactuating switch assemblies which start and stop various work functions within the appliance such as a rinse function in the case of a clothes washer. The switch assemblies within the appliance timer are actuated and deactuated as a result of interaction between a number of cam surfaces defined in a camstack of the appliance timer and a number of cam followers which are respectively associated with the switch assemblies.
The switch assemblies are generally grouped into a number of switch blocks associated with the appliance timer. For example, one common switch block configuration includes eight switch assemblies. Moreover, each of the switch assemblies typically includes an upper circuit blade and a lower circuit blade, with an intermediate circuit blade positioned therebetween. The circuit blades are moved into and out of contact with one another in order to make and break, respectively, a number of circuits. In particular, if the circuit blade has a cam follower molded or otherwise secured thereto, the circuit blade may be moved into and out of contact with other circuit blades via cooperation with one of the cam surfaces defined in the camstack. Alternatively, if the circuit blade is configured without a cam follower, the circuit blade will remain stationary until another circuit blade associated with the switch assembly is moved into or out of contact therewith. One common switch assembly arrangement includes an upper and a lower switch blade each of which is configured without a cam follower. Actuation of the switch assembly occurs as an intermediate circuit blade, which has a cam follower secured thereto, is selectively lifted into contact with the upper circuit blade or dropped into contact with the lower circuit blade.
One way to categorize appliance timers is by the number of switch blocks included in the timer. For example, appliance timers may be categorized as either "single block" timers or "double block" timers. As their respective names suggest, a single block timer includes a single switch block (e.g. a single group of eight switch assemblies in operative contact with the camstack), whereas a double block timer includes two switch blocks (e.g. two groups of switch assemblies each having eight switch assemblies in operative contact with the camstack).
Single block timers advantageously have fewer components relative to double block timers thereby reducing costs associated with the appliance timer. Hence, a number of single block timers have heretofore been designed for use in many household appliances. Such single block timers are used in conjunction with appliances which do not require the additional switching capacity associated with double block timers. For example, it is known that approximately 85% of the clothes washer and dishwasher models available in the appliance market may be operated with a single block timer. Therefore, use of single block timers in such appliances provides the switching capacity necessary to operate the appliance without the additional costs associated with double block timers.
However, the remaining models, often referred to as "high-end" models, generally must be controlled with a more complex timing device such as a double block timer. This is true since such high-end models generally have additional features associated therewith thereby increasing the number of switches required for operation of the appliance. As alluded to above, while use of such double block timers increases the switching capacity associated with the timer, costs associated with the timer are also increased thereby disadvantageously increasing costs associated with the appliance.
What is needed therefore is an appliance timer which has greater switching capacity relative to single block timers which have heretofore been designed. What is further needed is an appliance timer which has greater switching capacity relative to single block timers which have heretofore been designed, but has fewer components relative to double block timers which have heretofore been designed.